Background

Tauopathies are a group of neurodegenerative disorders with accumulation of three-repeat (3R) or four-repeat (4R) Tau. While 3R tau is found in Pick's disease and Alzheimer's disease (AD), 4R tau is more abundant in corticobasal degeneration, progressive supranuclear palsy, and AD. We have previously shown that Cerebrolysin™ (CBL), a neuropeptide mixture with neurotrophic effects, ameliorates the pathology in amyloid precursor protein transgenic (tg) mouse model of AD and 4R tau, however it is unclear if CBL ameliorates the deficits and neuropathology in the mouse model of Pick's disease over expressing 3R tau.

Results

Mice expressing 3R tau (L266V and G272V mutations) under the mThy-1 promoter were treated with CBL in two separate groups, the first was 3 months old (treated for 3 months, IP) and the second was 6 months old (treated for 3 months, IP) at the start of the treatment. We found that although the levels of total 3R tau were unchanged, CBL reduced the levels of hyper-phosphorylated tau in both groups of mice. This was accompanied by reduced neurodegenerative pathology in the neocortex and hippocampus in both groups and by improvements in the behavioral deficits in the nest-building test and water maze in the 3-6 month group.

Conclusion

Taken together these results support the notion that CBL may be beneficial in other taupathy models by reducing the levels of aberrantly phosphorylated tau.

Abnormal accumulation and propagation of the neuronal protein α-synuclein has been hypothesized to underlie the pathogenesis of Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Here we report a de novo-developed compound (NPT100-18A) that reduces α-synuclein toxicity through a novel mechanism that involves displacing α-synuclein from the membrane. This compound interacts with a domain in the C-terminus of α-synuclein. The E83R mutation reduces the compound interaction with the 80-90 amino acid region of α-synuclein and prevents the effects of NPT100-18A. In vitro studies showed that NPT100-18A reduced the formation of wild-type α-synuclein oligomers in membranes, reduced the neuronal accumulation of α-synuclein, and decreased markers of cell toxicity. In vivo studies were conducted in three different α-synuclein transgenic rodent models. Treatment with NPT100-18A ameliorated motor deficits in mThy1 wild-type α-synuclein transgenic mice in a dose-dependent manner at two independent institutions. Neuropathological examination showed that NPT100-18A decreased the accumulation of proteinase K-resistant α-synuclein aggregates in the CNS and was accompanied by the normalization of neuronal and inflammatory markers. These results were confirmed in a mutant line of α-synuclein transgenic mice that is prone to generate oligomers. In vivo imaging studies of α-synuclein-GFP transgenic mice using two-photon microscopy showed that NPT100-18A reduced the cortical synaptic accumulation of α-synuclein within 1 h post-administration. Taken together, these studies support the notion that altering the interaction of α-synuclein with the membrane might be a feasible therapeutic approach for developing new disease-modifying treatments of Parkinson's disease and other synucleinopathies.